/*
 * @(#)PrimeIterable.java	1.0 Apr 26, 2008
 *
 *	The MIT License
 *
 *	Copyright (c) 2008 Malachi de AElfweald <malachid@gmail.com>
 *
 *	Permission is hereby granted, free of charge, to any person obtaining a copy
 *	of this software and associated documentation files (the "Software"), to deal
 *	in the Software without restriction, including without limitation the rights
 *	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *	copies of the Software, and to permit persons to whom the Software is
 *	furnished to do so, subject to the following conditions:
 *
 *	The above copyright notice and this permission notice shall be included in
 *	all copies or substantial portions of the Software.
 *
 *	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *	THE SOFTWARE.
 */
package org.eoti.math.prime;

import java.math.BigInteger;
import java.util.*;

public class PrimeIterable
implements Iterable<BigInteger>
{
	protected boolean includeOne;

	public static void main(String[] args)
	{
		BigInteger idx = BigInteger.ONE;
		for(BigInteger prime : (new PrimeIterable(true)))
		{
			System.out.format("%s:\t%s\n", idx, prime);
			idx = idx.add(BigInteger.ONE);
		}
	}

	public PrimeIterable(boolean includeOne)
	{
		this.includeOne = includeOne;
	}

	public Iterator<BigInteger> iterator()
	{
		return new PrimeIterator(includeOne);
	}

	class PrimeIterator
	implements Iterator<BigInteger>
	{
		protected BigInteger prime, primeMinus1, factorial, toRet;

		public PrimeIterator(boolean includeOne)
		{
			prime = BigInteger.ONE;
			primeMinus1 = BigInteger.ZERO;
			factorial = BigInteger.ONE;

			if(!includeOne) next();
		}

		public boolean hasNext()
		{
			return true;
		}

		public BigInteger next()
		{
			while(!factorial.mod(prime).equals(primeMinus1))
				increment();

			toRet = prime;
			increment();
			return toRet;
		}

		protected void increment()
		{
			prime = prime.add(BigInteger.ONE);
			primeMinus1 = primeMinus1.add(BigInteger.ONE);
			factorial = factorial.multiply(primeMinus1);
		}

		public void remove()
		{
			throw new UnsupportedOperationException("Remove is not supported.");
		}
	}
}
